1. Field of the Invention
The invention relates to a torque-measuring shaft comprising a measuring shaft disposed on a shaft axis of the torque-measuring shaft, loadable in torsion and having at least one rotationally symmetric surface region disposed coaxially with the shaft axis as well as measuring means disposed on the measuring shaft for measuring a torsion of the measuring shaft.
2. Description of the Related Art
Torque-measuring shafts of the class in question are already known from the prior art.
For example, US 2002/0050177 A1 discloses a torque-measuring detector integratable in a drive-shaft train. The detector has a first torque-detector part comprising a sensor for the detecting of torsions and a second torque-detector part comprising a sensor for the detecting of torsions smaller than are detectable with the first torque-detector part, in order to be able to measure even smaller torques effectively and reliably.
From DE 10 2010 034 638 A1, a torque-measuring shaft is known with a first measuring region with a high sensitivity as well as a low torsional stiffness and with a second measuring region with a low sensitivity as well as a high torsional stiffness. For the increase of the torsional stiffness, this torque-measuring shaft further comprises spring elements disposed in alignment with a central measuring bar and stops therefor, wherein these spring elements are able to be braced against the stops during increasing torsion of the torque-measuring shaft, in order to increase the torsional stiffness of the torque-measuring shaft, thus permitting a high measuring sensitivity with a broad bandwidth.
Furthermore, from DE 10 2011 116 561 A1, a torque-measuring shaft is known with a torsion member disposed between two flanges. The torsion member is formed with differing thickness in the direction of its longitudinal extent and has a first and a second measuring zone. Both the first measuring zone and also the second measuring zone are loadable over the entire loading range of the torque-measuring shaft with a torque applied between the flanges. In this way, the various measuring zones can be structurally realized more simply.
In DD 250 996 A1, a multi-stage torque-torsion converter for torque-measuring devices is described, by means of which different measuring ranges are supposed to be adjusted. For this purpose the multi-stage torque-torsion converter has a torsion unit and a torsionally stiff coupling unit, wherein the torsion and coupling units are actively connected to one another by means of coupling claws at one end and are formed to be longitudinally positionable relative to one another by means of a spacing sleeve at the other end.
DE 35 28 364 A1 discloses a reaction-torque transducer in the form of a torsion tube loadable in torsion, which is bounded by two flanges. The reaction-torque transducer further has, mounted on the torsion tube, an electro-mechanically acting converter system, which consists substantially of strain gauges mounted symmetrically on the torsion tube. A circumferential recess is formed on the inside of the torsion tube in the region of the active part of the grid of the strain gauges. With this circumferential recess it is intended to ensure that the torsion tube is weakened only in the region destined for the converters.
Furthermore, from DE 40 09 286 A1, a measuring element with a flatly shaped strain-gauge array of at least one metallic strain gauge and associated metallic contact faces is known, which is characterized by a flat diaphragm, which is formed in one piece with a thickened flange, oriented along the rim of the diaphragm, which serves for the fastening of the measuring element to a member, the torsion of which is to be measured, wherein the strain-gauge array is firmly mounted on one side of the diaphragm.
DE 195 25 231 A1 discloses a torque sensor with two flanges disposed at axial spacing, wherein the flanges are joined to one another via several axially extending webs and wherein the webs have shearing-force measured-value transducers in the form of strain gauges. These webs have at least one face resting substantially on a common cylinder face coaxial with the flanges, wherein the strain gauges are disposed on this face. The torque sensor is intended to combine a good measuring accuracy with a high insensitivity toward interfering forces.
From DE 199 36 293 A1, a torque sensor is known with a first and a second flange, which are spaced axially apart from one another and which are joined to one another via a torque-transmitting element, wherein the torque-transmitting element has weakened regions, which possess, coaxially with the flanges, at least one common shell surface, on which shearing-force measured-value transducers are disposed. The torque-transmission element has a closed tubular portion connecting the flanges, whereby the torque sensor has a compact construction.
DE 10 2007 005 894 A1 describes a torque-measuring flange with a substantially cylindrical measuring region, in which measuring recesses are disposed, and with measured-value transducers, which measure stresses and/or strains in the measuring region, wherein at least two measuring recesses are shaped differently, whereby several higher or several differently resolved measuring regions can be provided with a single torque-measuring flange.
Furthermore, from DE 10 2008 028 826 A1, a torque-measuring device with a torque-measuring flange and an evaluating unit is known, in which the evaluating unit has means for the storage of a variable proportional to a freewheel torque and means for the compensation for a measured value with the stored variable, in order to minimize in particular the measurement of artifacts.
Furthermore, the disclosure of DE 196 40 717 A1 shows a torsionally stiff torque-measuring hub for the static and dynamic sensing of torques. This torque-measuring hub consists substantially of two rotationally symmetric disks, which at their circumference are joined frictionally to one another with largest possible spacing R from the axis of rotation by axially aligned force transducers. The force transducers are dimensioned for the sensing of shearing tangential forces.
In addition, WO 2009/155049 A2 also teaches a torque transmitting and monitoring device with a first and a second flange part for the arrangement of the torque, transmitting and monitoring device in a drive train, wherein the two flange parts spaced apart from one another by a gap are joined to one another with a middle part. On the shell surfaces of the two flange parts, a cylindrical band bridging over the gap is disposed which circumferentially has a toothing, the individual teeth elements of which change relative to one another upon a torsion of the middle part and a relative shift of the two flange parts resulting therefrom. These changes are detected by a sensor provided further outward radially, whereby the stronger of the torques can be determined.
In the torque-measuring shafts mentioned in particular in the foregoing, it is disadvantageous that they either have a relatively complex constructive structure and/or are not suitable for use into a high-speed range of extremely small rotating shafts or the like.